A plasma processing apparatus such as a radial line slot antenna apparatus, or the like generates plasma and performs minute processing on a processed body such as a wafer or a substrate by the action of the plasma, thereby manufacturing a semiconductor device. In the plasma processing apparatus, it is important to uniformly generate plasma. In particular, in recent years, minuteness has been in progress due to a request for high integration and rapidness of an LSI. Further, the processed body is enlarged. Under the circumstances, uniformity of plasma becomes more important in order to successfully microfabricate the processed body.
Therefore, a radial line slot antenna apparatus is proposed, which has a mechanism for suppressing damage of an element by improving electron density or uniformity of plasma (see, for example, International Publication No. WO2008/108213). According to International Publication No. WO2008/108213, a magnetic field forming portion is formed at an upper side of an antenna for introducing a microwave, which is provided in the radial line slot antenna apparatus, and a plasma feature of gas generated in a processing container by the microwave is controlled by a magnetic field formed by the magnetic field forming portion.